Tds. Help

[no1bubba]

I have three meters and they are al 6 apart. Tap 114. RODI. 120
Is it time to change the resin in my 7 stage RODI

 

[mcgyvr]

Huh?..states 3 meters...2 posted numbers?.. None close to zero..
Been smokin the resin maybe?

 

[no1bubba]

I own three different meters none of the three ever read the same but they all read a difference of 6 between tap and RODI. I found a formula this minus that divided by tap water times 1000. I THINK but I can't remember. What I keep coming up with is 0.0052. Don't know who figured it that way for me but what I want to know does it make any sense to any one. I always change resin according to color change but I think I may be wasting resin because I only do 20 gal water change weekly and it has only been 2 months. I need your wisdom not your "œwhit"?

 

[mcgyvr]

Im sorry..I do not understand what you are trying to say..
Many would say the resin is spent when the output tds is greater than zero..some will wait till greater than 1 or 2

 

[nereefpat]

Your tap water has a TDS of 114 ppm? That sounds reasonable.

If that is the case, then a properly functioning RO should bring TDS down to about 5-10 ppm. If after the RO, the TDS isn't in that range, then we need to fix that.

The DI should bring the TDS down from 5-10 to zero. If the DI output isn't zero, then you need to replace the resin. But it seems like you have more problems then DI resin.

So, let's start at the beginning. What are the TDS readings for tapwater, RO, and RODI? Just pick one of the meters to use. The 6ppm difference isn't important, for now.

 

[no1bubba]

Tap 114. RODI 120

 

[WVfishguy]

Tap 114. RODI 120

Are you saying your tap water has a TDS of 114 - which is WAY low for tap water in PA - but your RODI has a TDS of 120? Your RODI is increasing the TDS?

If so, you certainly need to flush your system, change resin, and do anything else the reefers here recommend. Your posts are quite vague.

 

[Uncle99]

Tap 114. RODI 120

If your tap is 114ppm, then, after your filter process is 120ppm, this would mean your RO membrane is gone, you'll need to replace that filter membrane.

The 6 point difference is minor at this point.

 

[nereefpat]

Yep. The RO is either shot or not installed correctly.

I wouldn't try to deal with the DI until the RO is dropping TDS at least 90%. Make sure the membrane is seated correctly and the flow is going the right direction, for starters.

 

[dkevink]

I wish my tap was 114. Mine tap water is 950 in Ohio. I have to use water softener, then rodi. I have to be careful not to cross contaminate anything from tap water.